1. Field of the Invention
The present invention relates to a multicolor dye set with high chroma and an inkjet ink composition using the dye set.
2. Background of the Invention
Color ink for color inkjet printing requires a wide color range and ideal color matching. A primary dye set includes cyan ink, magenta ink, yellow ink, and black ink. A secondary dye set includes other colorants obtained from combining the dyes of the primary dye set.
A successful ink composition for color inkjet printing must meet the following requirements: good crusting resistance, good stability, proper viscosity, proper surface tension, high color saturation, little color-to-color bleed, and rapid dry time. In addition, a successful ink composition can be ejected onto plain paper without kogation.
Color can be specified by two systems: color appearance system and color mixing system. Color appearance system is a system obtained from collecting data of actual colored objects and systematically generalizing the data. Examples include the Ostwald color system, the Munsell color system, and the DIN color system. Color mixing system is based on the principle that primary color stimuli can be matched to generate various colors. Presently, the most important color mixing system is the CIE colorimetric system, which measures color instrumentally. For example, the Munsell color system was developed by Munsell, an American painter, and is the most famous system, describing color by hue, value, and chroma. For the CIE colorimetric system, the color stimuli (stimuli X, Y, and Z) and sensation of color are caused by the incorporation of light sources, objects, and observers. Color space is defined by three values L*, a*, and b*. L* indicates the lightness of a color, a* the hue, and b* the chroma of a color. a* ranges from xe2x88x92a (green) to +a (red), and b* ranges from xe2x88x92b (blue) to +b (yellow). In 1976, the CIE system further incorporates hue angle (h0) and chroma (C*) (see Formula 1 and 2). In the CIELAB color space, color difference (xcex94E) indicates the color difference between two color samples (see Formula 3). The greater the xcex94E, the greater the color difference between two color samples.
h0=tanxe2x88x921(b*/a*)xe2x80x83xe2x80x83Formula 1
C*=(a*2+b*2)1/2xe2x80x83xe2x80x83Formula 2
xcex94E=(xcex94L*2+xcex94a*2+xcex94b*2)1/2xe2x80x83xe2x80x83Formula 3
Therefore, when an ideal ink composition is used to conduct inkjet printing, it must provide ultimate color characteristics, such as good hue and high chroma.
Generally speaking, if the ink for inkjet printing includes only one colorant, it easily causes clogging at the nozzle. Therefore, many kinds of humectants are generally added. However, this frequently causes a slower drying rate and poor water-fastness. For example, in U.S. Pat. No. 4,631,085 (1986), U.S. Pat. No. 4,713,113 (1987), and U.S. Pat. No. 4,737,190 (1988), the ink includes a single colorant, and a humectant is required to prevent coagulation. U.S. Pat. No, 5,925,177 (1999) discloses an ink composition including Acid Yellow 23 dye, urea, and water. The addition of urea can prevent clogging of the nozzles resulting from crystallization of the yellow dye.
The ink composition for color inkjet printers generally includes four kinds of ink, magenta ink, cyan ink, yellow ink, and black ink, which are mainly water-based dyes. In recent years, the ink composition includes six kinds of ink, that is, magenta ink, cyan ink, yellow ink, black ink, light magenta ink, and light cyan ink, or seven kinds of ink with an additional light yellow ink. The ink composition includes at least one water-based (water-soluble) dye, water, an organic solvent, and other additives. However, such dye-based water-based ink has inferior water-fastness and light-fastness.
Thus, pigment-based inks with good water-fastness and light-fastness have been developed in recent years. Such ink includes at least one pigment, water, an organic solvent, and other additives. The inkjet ink using pigment as the colorant has better water-fastness and light-fastness than a dye-based ink. However, dispersants or adhesives must be added to the pigment-based ink. In addition, pigment has a larger particle size, which easily causes precipitation and coagulation, thus clogging the nozzle and negatively impacting printing properties.
One object of the present invention is to provide a water-soluble multicolor dye set and a multicolor inkjet ink composition with high chroma.
The second object of the present invention is to provide a novel water-soluble cyan dye set and a cyan inkjet ink composition including the dye set.
The third object of the present invention is to provide a novel water-soluble magenta dye set and a magenta inkjet ink composition including the dye set.
To achieve the above-mentioned objects, the water-soluble cyan dye set of the present invention includes Direct Blue 199 dye, Acid Blue 9 dye, and Direct Blue 87 dye.
The water-soluble magenta dye set of the present invention includes Reactive Red 158 dye, Reactive Red 159 dye, and Acid Red 92 dye.
The water-soluble multicolor dye set with high chroma of the present invention includes (1) Direct Blue 199 dye, Acid Blue 9 dye, and Direct Blue 87 dye; (2) Reactive Red 158 dye, Reactive Red 159 dye, and Acid Red 92 dye; and (3) Acid Yellow 23 dye and Direct Yellow 86 dye.
The inkjet ink composition of the present invention includes the above dye set, an aqueous solution, and other additives. The additives can be, but are not limited to, organic solvents, surfactants, pH buffer additives, chelating agents, biocides, humectants, preservatives, or UV blockers. The ink composition of the present invention has not only excellent light-fastness and water-fastness, but also broader color space and high quality color image.